JP2008139660A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To most efficiently use (reuse) toner in a black station in which usage rate is high in a color image forming apparatus without increasing environmental load, to prevent occurrence of an abnormal image due to reuse, and to provide a high-quality image. <P>SOLUTION: In the color image forming apparatus having a plurality of image forming stations each including an image carrier, a developing device and a structure for recovering used toner from the image carrier, the image forming station for black is provided with a mechanism for returning recovered used toner to the developing device. In black-and-white printing, image formation is performed with only the image forming station for black and residual toner on the image carrier is returned to the developing device. In color printing, a primary transfer means for the image forming station for black is removed in a direction in which it is moved away from the corresponding image carrier, the image carrier is separated from an intermediate transfer means or a recording medium, and image formation is performed with only the other image forming stations. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a fax machine using an electrophotographic system. In particular, the present invention relates to an image forming apparatus that can effectively use black toner.

  In an electrophotographic image forming apparatus, after a toner image formed on an image carrier is transferred to a transfer target, residual toner that remains on the image carrier without being transferred is removed by a cleaning unit. . In recent years, from the viewpoint of effective use of resources and reduction of environmental load, it has been required to reuse removed toner without discarding it, and transfer the toner collected by the cleaning means to the developing device or toner replenishing device. Many toner recycling mechanisms have been proposed for reuse. In a monochrome image forming apparatus, there is no problem if the waste toner is returned to the developing unit and reused, but in a color machine, the reverse transfer toner from the intermediate transfer means or the recording medium (transfer paper, OHP, etc.) is cleaned. There is a problem that the waste toner is mixed by entering the means, and the original color cannot be reproduced. The movement of toner in a black station in a general color image forming apparatus will be described with reference to FIG. On the intermediate transfer member or the recording medium, the toner already transferred at the other color station on the upstream side is present, and enters the position (transfer nip) where the photosensitive member and the primary transfer means in the black station face each other. On the other hand, on the photosensitive member, the toner image developed at the black station enters the transfer nip of the black station. At the transfer nip of the black station, the black toner image on the photosensitive member is transferred to the intermediate transfer unit or the recording medium. The electric force at that time causes the toner image already on the intermediate transfer unit or the recording medium to be transferred. A part of the image is reversely transferred onto the photosensitive member of the black station. The reverse transfer toner can be reduced by adjusting the current value applied to the transfer, but cannot be completely eliminated. In this way, the mixed color toner enters from the waste toner path through the cleaning unit.

  Regarding the reuse of waste toner, Patent Document 1 discloses that a means for detecting the amount of waste toner returned from the cleaning unit to the developing unit is provided, thereby correcting the replenishment amount from the toner replenishment unit. Although this method can grasp the amount of waste toner to be reused, it can sufficiently cope with the quantitative point, but has no effect on the problem of color mixing.

  The configuration proposed in Patent Document 2 allows the waste toner transport path to be switched between a path for returning to development (reuse) and a path for collecting to a waste toner tank (disposal). You can choose between reuse and disposal. This is a very effective means from the viewpoint of preventing color mixing. However, a configuration for switching the route is required, which increases the number of parts and may increase the environmental load.

  The proposal of Patent Document 3 is to provide a dedicated station for reuse, and print and recycle at the dedicated station for black monochrome printing. This method can also eliminate the problem of color mixing at the time of reuse, but it requires an additional station, which may increase the environmental load.

JP-A-8-146852 JP 2002-162883 A JP 2006-106375 A

  An object of the present invention is to use a black station toner with a high usage rate without waste in a color image forming apparatus without increasing the environmental load (reuse), and prevent occurrence of abnormal images due to reuse, The purpose is to provide high-quality images.

  According to the present invention, there is provided a color image forming apparatus having a plurality of image forming stations each having an image carrier, a developing device, and a structure for collecting waste toner from the image carrier. A mechanism is provided for returning the collected waste toner to the developing device. When performing monochrome printing, image formation is performed only at the black image forming station, and the residual toner on the image carrier is returned to the developing device. When performing color printing, the primary transfer means for the black image forming station is retracted away from the corresponding image carrier to separate the image carrier from the intermediate transfer means or the recording medium. This can be solved by forming an image only at another image forming station.

  In addition, when performing color printing, the image carrier of the black image forming station is retracted / separated in a direction away from the intermediate transfer unit or the recording medium, and the image is formed only by another image forming station. Is solved.

  Among the plurality of image forming stations, it is preferable that the black image forming station is disposed at a position other than the most upstream side in the moving direction of the intermediate transfer unit or the recording medium. The black image forming station is preferably configured as a process cartridge in which at least the image carrier and the cleaning unit are integrated.

  According to the first or second aspect of the invention, the black toner having a high usage rate can be reused without waste, and the occurrence of an abnormal image at the time of reuse can be prevented. According to the invention of claim 3, the two effects of solving the problem of color mixing and shortening the first copy are brought about simultaneously. According to the fourth aspect of the present invention, at least the cleaning means is integrated with the image carrier, so that it is possible to prevent waste toner leakage and waste toner dropping from the waste toner conveyance path.

An example of an image forming apparatus according to the present invention will be described with reference to FIG.
The image forming apparatus 100 includes a process station (90y, 90m, 90c, 90k) for forming a toner image of each color (y: yellow, m: magenta, c: cyan, k: black), an exposure device 30, and each color. An intermediate transfer belt 6 that superimposes and conveys the toner images, a paper storage portion P1 that stores the recording medium, a paper transport portion P2 that transports the paper, and a toner image on the intermediate transfer belt that transfers the toner image to the recording medium. Next transfer roller 62, fixing unit 8 provided with heating means using a belt or the like for fixing an unfixed toner image on the recording medium, and toner storage containers (52y, 52m, 52c, 52k) for storing unused toner And an image processing unit (not shown). Regarding the arrangement of process stations, the black station is often arranged at the most downstream position in the rotation direction of the intermediate transfer belt in order to shorten the first black copy (first print time). They are not interchangeable and can be interchanged. The more black stations are placed upstream, the longer the black first copy.

  A process cartridge in which the process station is formed into a cartridge will be described with reference to FIG. A process cartridge 90 (letters indicating the colors are omitted for simplicity) includes a photosensitive member 1 that is an image carrier, a charging roller 2, a developing device 4, and a cleaning blade that scrapes off transfer residual toner after transfer. 7. It is composed of a brush roller 9 for applying a lubricant for stabilizing the friction coefficient of the photosensitive member surface at a low level.

  As charging means, there are a scorotron method, a corotron method, which is charging by a wire, a contact roller charging method using a medium resistance rubber roller, and a non-contact roller charging method (in this example, a contact charging roller charging method). The Scorotron method was previously used for negatively charging the surface of a photoconductor. However, ozone is generated during discharge, so from the viewpoint of emphasizing the environment, there are currently only a limited number of models. not being used. In addition, the corotron method is for positively charging the photoconductor, and the generation of ozone is small, but it is not generally used. Recently, the generation of ozone can be suppressed and the unit price of the roller has been reduced, so the roller charging method is the most common charging means. For both the contact roller charging method and the non-contact roller charging method, there are a method of superimposing alternating current on direct current and a method of applying only direct current.

  In the case of the non-contact charging roller method, if alternating current is controlled at a constant current, the image will be uneven due to the influence of the gap fluctuation between the photosensitive member 1 and the charging roller 2, so that as in the case where only direct current is applied, A means for correcting the applied voltage is required. However, since it is non-contact, there is more room for contamination of the charging roller than the contact type. As a correction method, there are a method of detecting the temperature in the vicinity of the charging roller and switching the applied voltage, a method of periodically detecting ground contamination on the photosensitive member and switching the applied voltage, and a method of determining the applied voltage based on the feedback current value. is there. By taking these methods, the surface of the photoreceptor is charged to about -500V to -700V.

  In the contact roller charging method, when alternating current is superimposed on direct current, high image quality can be obtained as compared with direct current, but attention must be paid to the problem of filming of the photoreceptor. In addition, the constant current control of alternating current has the advantage that the surface potential is not affected by fluctuations in the resistance value of the charging roller due to environmental changes, but on the other hand, the cost of the high-voltage power supply becomes high and the sound of alternating high frequency is a problem. It is as. When only a direct current is applied, a change in the resistance value of the charging roller due to an environmental change affects the surface potential with respect to the environmental change, so some means for correcting the applied voltage is required.

  As a driving method for the charging roller 2, there are a method in which the photosensitive member 1 is brought into pressure contact and rotated by a frictional force, and a method in which a driving force is obtained from a photosensitive member gear or the like. In the case of a low speed machine, the former method is often used, but in the machine that requires high speed and high image quality, the latter method is often used.

  The image forming operation will be described with reference to FIGS. When performing monochrome printing, an image signal is sent to the exposure device 30 when an image output command is sent from an input device such as a PC or a scanner (not shown) to the image forming apparatus. As the exposure apparatus, for example, a laser scanning exposure method using a laser light source and a polygon mirror is used. At stations other than black (90y, 90m, 90c), the primary transfer roller 61 disposed facing the photoreceptor 1 is retracted away from the photoreceptor 1 (FIG. 3) or the photoreceptor 1 is an intermediate transfer belt. Retreat away from 6. Many configurations of the evacuation means are already known, any of which may be used, and a specific description thereof will be omitted. At this time, the photosensitive member 1 and the developing device 4 are not driven, and shortening of the life due to unnecessary driving is avoided. In the black station, the photoconductor 1 is driven, and the photoconductor 1 is uniformly charged by the charging roller 2. Thereafter, exposure according to the image signal is performed by the exposure device 30, and an electrostatic latent image is formed on the photoreceptor. The electrostatic latent image is developed by the developing roller 4 to be visualized as a toner image. The toner image on the photoreceptor is transferred to the intermediate transfer belt 6 by applying a bias to the transfer roller 61. The transfer residual toner remaining on the photoconductor after the transfer is removed from the photoconductor 1 by the cleaning blade 7 in which urethane rubber is brought into contact with the photoconductor 1 in the counter direction, and is conveyed by the waste toner collecting coil 10. The toner is returned to the developing device 4 through a conveyance path (not shown). In order to make up for the consumed toner that is not sufficient for recovery, the toner is supplied from the toner storage container 52 to the developing device 4 using a toner supply means. For example, the recording medium passes from the paper storage portion P1 through the paper conveyance portion P2, and the toner image is transferred by the secondary transfer roller 62. When the recording medium on which the unfixed toner image is placed proceeds to the fixing unit 8, the toner is fused and fixed to the recording medium by heat and pressure. Then, the image is output to the outside of the image forming apparatus and the image formation is completed.

  When performing color printing, when an image output command is sent to an image forming apparatus from an input device such as a PC or a scanner (not shown), the image signal is image-processed by the image processing unit and separated into signals of each color (YMC). After that, it is sent to the exposure apparatus 30. The black portion in the color image is prepared by overlapping cyan, magenta, and yellow. In the black station 90k, the primary transfer roller 61 disposed opposite to the photosensitive member 1 is retracted away from the photosensitive member 1 (FIG. 4), or at least the photosensitive member 1 among the components constituting the black station is in the middle. The photosensitive member 1 and the intermediate transfer belt are separated from each other by retracting away from the transfer belt 6. Thereby, it is possible to avoid the reverse transfer toner of other colors from being mixed with the waste toner of the black station, and it is possible to prevent the problem of color mixing when using the recycled toner. Many configurations of the evacuation means are already known, any of which may be used, and a specific description thereof will be omitted. It is important to switch the station that performs the evacuation operation depending on whether the printed image is monochrome or color, and the evacuation method is not limited. At that time, the photosensitive member 1 and the developing device 4 are not driven. In addition to avoiding shortening of service life due to wasteful driving, waste toner accumulated in the waste toner path even when toner in the black station developing device is not consumed at all when color printing occurs continuously Returns to the developing device. This is because there is a possibility that the toner density in the developing device may be greatly shifted. In other color stations, the photoreceptor 1 is driven, and the photoreceptor 1 is uniformly charged by the charging roller 2. Thereafter, exposure according to the image signal is performed by the exposure device 30, and an electrostatic latent image is formed on the photoreceptor. The electrostatic latent image is developed by the developing roller 4 to be visualized as a toner image. The toner image on the photoreceptor is transferred to the intermediate transfer belt 6 by applying a bias to the transfer roller 61. The untransferred toner remaining on the photoconductor after the transfer is removed from the photoconductor by a cleaning blade 7 in which urethane rubber is brought into contact with the photoconductor 1 in the counter direction, conveyed by a waste toner collecting coil 10, and unreacted. It is accommodated in the illustrated waste toner tank. In order to make up for consumed toner, toner is supplied from the toner storage container 52 to each developing device 4 using toner supply means. The transfer of the toner image onto the intermediate transfer belt 6 is sequentially performed from the process stations (90y, 90m, 90c) of the respective colors, and the toner images of the respective colors are superimposed on the intermediate transfer belt. For example, the recording medium passes from the paper storage portion P1 through the paper conveyance portion P2, and the toner image is transferred by the secondary transfer roller 62. When the recording medium on which the unfixed toner image is placed proceeds to the fixing unit 8, the toner is fused and fixed to the recording medium by heat and pressure. Then, the image is output to the outside of the image forming apparatus and the image formation is completed.

  FIG. 5 shows an embodiment in which color printing is performed in the “direct transfer type” image forming apparatus in which the recording medium moves on the transfer belt and the image is directly transferred from the photosensitive member, and FIG. 6 shows the process cartridge. This method eliminates the need for secondary transfer, but has the disadvantage that the photosensitive member and cleaning are easily affected by paper dust. Also, since paper dust is mixed with the collected waste toner, it is less suitable in terms of waste toner recycling than the intermediate transfer type image forming apparatus described above.

  Here, the flow up to the start of the image forming operation will be described with reference to FIG. After receiving printing execution (print command from PC, start button of copy machine, etc.), it is determined whether the command is monochrome output or color output. In the case of monochrome output, the primary transfer roller facing the photoconductor of a color station other than black is retracted away from the photoconductor, or at least the photoconductor among the components constituting the color station is an intermediate transfer belt or recording. By retracting in a direction away from the medium, the color station (yellow, magenta, cyan) photosensitive member is separated from the intermediate transfer belt or the recording medium. Conversely, in the case of color output, the primary transfer roller facing the photosensitive member of the black station is retracted in a direction away from the photosensitive member, or at least the photosensitive member among the components constituting the black station is the intermediate transfer belt or the recording medium. By retracting in the direction away from the photosensitive member, the photosensitive member of the black station is separated from the intermediate transfer belt or the recording medium. The separation is preferably detected by a sensor or the like. After the separation is confirmed, the photosensitive member and the developing device are activated to start a printing operation.

  Next, dirt on the charging roller 2 will be described. When the surface of the charging roller 2 is soiled, the charging ability of the soiled portion is reduced and the photoreceptor 1 cannot be charged to the target potential. As a result, an abnormal image of defective charging appears. In order to prevent this, a charging roller cleaner (cleaning roller 11) is brought into contact. As the charging roller cleaner, it is possible to use a flocking roller in which fibers are electrostatically flocked on a metal shaft, or a melamine roller with a melamine resin placed on the roller around the metal shaft. Therefore, the use of a melamine roller is recommended.

  If slip occurs between the cleaning roller 11 and the charging roller 2, dirt is rubbed against the surface of the charging roller, and the generation of an abnormal image due to the dirt is accelerated. In view of this, the charging roller cleaner is made to follow the charging roller 2 without being driven to remove the dirt on the surface of the charging roller. When the drive is applied, a slipping state is inevitably caused by the tolerance of the charging roller diameter and the diameter tolerance of the charging roller cleaner, and the life is shortened. Ideally, it is desirable that the surface moving speed is the same at the contact portion between the charging roller 2 and the cleaning roller 11 (no slip).

  In the process cartridge 90 shown in FIG. 2, the cleaning roller 11 is brought into contact with the charging roller 2 obliquely from below. Therefore, there are a pressure spring 12 for the charging roller and a pressure spring 13 for the cleaning roller. When the configuration of the process cartridge is changed as shown in FIG. 6, the cleaning roller 11 is brought into contact with the charging roller 2 from above, so that a pressure spring is not required and only the weight of the roller is sufficient.

  A lubricant is applied to the surface of the photoconductor to prevent photoconductor filming. The lubricant 14 is in pressure contact with the lubricant application brush roller 9 by the action of the pressure spring 15 and is gradually scraped by the rotation of the lubricant application brush roller 9. It is applied to the surface. The lubricant applied to the surface of the photoreceptor by the lubricant application brush roller 9 is fixed to the surface of the photoreceptor with a uniform thickness by the lubricant application blade 16. As the lubricant, ZnSt (zinc stearate) is most commonly used. As the brush roller 9, insulating PET, conductive PET, acrylic fiber, or the like is used.

  Next, characteristics of the toner preferably used in the image forming apparatus according to the present invention will be described. In order to stably reproduce a minute dot image of 600 dpi or more, the toner preferably has a weight average particle diameter of 3 to 8 μm. In this range, since the toner has a sufficiently small particle diameter with respect to a minute latent image dot, the dot reproducibility is excellent. On the other hand, when the weight average particle diameter (D4) is less than 3 μm, phenomena such as a decrease in transfer efficiency and a decrease in blade cleaning properties are likely to occur. When the weight average particle diameter (D4) exceeds 8 μm, the pile height of the image becomes large, and it is difficult to suppress scattering of characters and lines.

  At the same time, the ratio (D4 / D1) of the weight average particle diameter (D4) to the number average particle diameter (D1) is preferably in the range of 1.00 to 1.40. The closer (D4 / D1) is to 1.00, the sharper the particle size distribution. With such a toner having a small particle size and a narrow particle size distribution, the toner charge amount distribution is uniform, a high-quality image with little background fogging can be obtained, and the electrostatic transfer method increases the transfer rate. be able to.

  Next, a method for measuring the particle size distribution of toner particles will be described. As an apparatus for measuring the particle size distribution of toner particles by the Coulter counter method, there can be mentioned Coulter Counter TA-II and Coulter Multisizer II (both manufactured by Coulter). The measurement method is described below. First, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution. Here, the electrolytic solution is a solution prepared by preparing a 1% NaCl aqueous solution using primary sodium chloride. For example, ISOTON-II (manufactured by Coulter) can be used. Here, 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the measurement device is used to measure the weight and number of toner particles or toner using a 100 μm aperture as an aperture. Calculate weight distribution and number distribution. From the obtained distribution, the weight average particle diameter (D4) and the number average particle diameter (D1) of the toner can be obtained.

  As channels, 2.00 to less than 2.52 μm; 2.52 to less than 3.17 μm; 3.17 to less than 4.00 μm; 4.00 to less than 5.04 μm; 5.04 to less than 6.35 μm; 6 Less than 35 to 8.00 μm; less than 8.00 to less than 10.08 μm; less than 10.08 to less than 12.70 μm; less than 12.70 to less than 16.00 μm; less than 16.00 to less than 20.20 μm; Uses 13 channels of less than 40 μm; 25.40 to less than 32.00 μm; 32.00 to less than 40.30 μm, and targets particles having a particle size of 2.00 μm to less than 40.30 μm.

The toner shape factor SF-1 is preferably in the range of 100 to 180, and the shape factor SF-2 is preferably in the range of 100 to 180. 8 and 9 are diagrams schematically showing the shape of the toner in order to explain the shape factor SF-1 and the shape factor SF-2. The shape factor SF-1 indicates the ratio of the roundness of the toner shape, and is represented by Expression (1). This is a value obtained by dividing the square of the maximum length MXLNG of the shape formed by projecting the toner on a two-dimensional plane by the figure area AREA and multiplying by 100π / 4.
SF-1 = {(MXLNG) 2 / AREA} × (100π / 4) (1)
When the value of SF-1 is 100, the shape of the toner becomes a true sphere, and becomes larger as the value of SF-1 increases.

The shape factor SF-2 indicates the ratio of the unevenness of the toner shape, and is represented by the formula (2). A value obtained by dividing the square of the perimeter PERI of the figure formed by projecting the toner onto the two-dimensional plane by the figure area AREA and multiplying by 100 / 4π.
SF-2 = {(PERI) 2 / AREA} × (100 / 4π) (2)
When the value of SF-2 is 100, unevenness does not exist on the toner surface, and the unevenness of the toner surface becomes more prominent as the value of SF-2 increases.

  Specifically, the shape factor is measured by taking a photograph of the toner with a scanning electron microscope (S-800: manufactured by Hitachi, Ltd.), introducing it into an image analyzer (LUSEX 3: manufactured by Nireco) and analyzing it. calculate. When the shape of the toner is close to a sphere, the contact state between the toners or between the toner and the photosensitive member becomes a point contact, so that the attractive force between the toners is weakened. As a result, the transfer rate increases. If either of the shape factors SF-1 and SF-2 exceeds 180, the transfer rate is lowered, which is not preferable.

In the toner according to the present invention, fine particles (hereinafter, simply referred to as fine particles) having an average primary particle size of 50 to 500 nm and a bulk density of 0.3 mg / cm ³ or more are adhered to the toner particle surface. By using fine particles having an average primary particle size of 50 to 500 nm and a bulk density of 0.3 mg / cm ³ or more as an external additive, a small particle size toner having good cleaning properties and particularly achieving high image quality. When used, improvement in developability and transferability is improved. In addition, although silica etc. are often used for a normal fluid improvement agent, for example, the average primary particle diameter of this silica is 10-30 nm normally, and a bulk density is 0.1-0.2 mg / cm < ³ >.

  Due to the presence of fine particles having appropriate characteristics on the surface of the toner, an appropriate gap is formed between the toner particles and the object. Further, the fine particles have a very small contact area with the toner particles, the photoconductor, and the charge imparting member and are in uniform contact with each other, so that the effect of reducing the adhesive force is great and effective in improving the development / transfer efficiency. Furthermore, since it acts as a roller, it does not wear or damage the photoconductor, and it is difficult to embed it in toner particles even when cleaning the cleaning blade and photoconductor under high stress (high load, high speed, etc.). Or, even if it is buried a little, it can be detached and returned, so that stable characteristics can be obtained over a long period of time. Further, the toner is moderately detached from the surface of the toner and accumulated at the tip of the cleaning blade, and the so-called dam effect has an effect of preventing a phenomenon that the toner passes from the blade. Since these characteristics have an effect of reducing the share received by the toner particles, the filming effect of the toner itself due to the low rheological component contained in the toner is exhibited for high-speed fixing (low energy fixing). In addition, when fine particles having an average primary particle size in the range of 50 to 500 μm are used, the excellent cleaning performance can be fully utilized, and since the particle size is extremely small, the powder fluidity of the toner is improved. There is no reduction. Further, although details are not clear, the surface-treated fine particles have a small degree of developer deterioration even if they are externally added to the toner or if the carrier is contaminated.

The average primary particle size (hereinafter referred to as the average particle size) of the fine particles is 50 to 500 nm, and particularly preferably 100 to 400 nm. If it is less than 50 nm, the fine particles are buried in the concave and convex portions of the toner surface, and the effect of reducing the adhesion cannot be obtained. On the other hand, if the thickness is larger than 500 nm, the contact area is on the same level as the contact area of the toner itself, the adhesion reduction effect cannot be obtained, and the transfer rate improvement and stress reduction effect cannot be obtained. When the bulk density is less than 0.3 mg / cm ³ , although there is a contribution to improving the fluidity, the scattering property and adhesion of the toner and fine particles are increased, and thus the effect of reducing the adhesion force cannot be obtained.

In the fine particles of the present invention, the inorganic compounds include SiO ₂ , TiO ₂ , Al ₂ O ₃ , MgO, CuO, ZnO, SnO ₂ , CeO ₂ , Fe ₂ O ₃ , BaO, CaO, K ₂ O, Na ₂ O. , ZrO ₂ , CaO · SiO ₂ , K ₂ O (TiO ₂ ) _n , Al ₂ O ₃ · 2SiO ₂ , CaCO ₃ , MgCO ₃ , BaSO ₄ , MgSO ₄ , SrTiO _{3 and the} like, preferably Examples thereof include SiO ₂ , TiO ₂ , and Al ₂ O ₃ . In particular, these inorganic compounds may be hydrophobized with various coupling agents, hexamethyldisilazane, dimethyldichlorosilane, octyltrimethoxysilane, and the like.

  The organic compound fine particles may be thermoplastic resins or thermosetting resins, such as vinyl resins, polyurethane resins, epoxy resins, polyester resins, polyamide resins, polyimide resins, silicon resins, phenol resins, melamine resins, Examples include urea resin, aniline resin, ionomer resin, and polycarbonate resin. As the resin fine particles, two or more of the above resins may be used in combination. Of these, vinyl resins, polyurethane resins, epoxy resins, polyester resins, and combinations thereof are preferred because an aqueous dispersion of fine spherical resin particles is easily obtained.

  Specific examples of vinyl resins include polymers obtained by homopolymerization or copolymerization of vinyl monomers, such as styrene- (meth) acrylic acid ester copolymers, styrene-butadiene copolymers, (meth) acrylic acid. -Acrylic ester copolymer, styrene-acrylonitrile copolymer, styrene-maleic anhydride copolymer, styrene- (meth) acrylic acid copolymer and the like.

The bulk density of the fine particles was measured by the following method. Using a 100 ml graduated cylinder, fine particles were gradually added to make 100 ml. At that time, no vibration was applied. The bulk density was measured by the difference in weight before and after placing the fine particles of the graduated cylinder.
Bulk density (g / cm ³ ) = fine particle amount (g / 100 ml) ÷ 100

  The fine particles according to the present invention can be externally added and adhered to the toner surface by mechanically mixing and adhering the toner base particles and fine particles using various known mixing devices, or in the liquid phase. There is a method in which base particles and fine particles are uniformly dispersed with a surfactant or the like, and dried after the adhesion treatment.

  Many toner characteristics related to toner fixing properties are known, and in particular, it is known that 1/2 outflow temperature (softening point) is related. In the present invention, 1/2 outflow temperature (softening point) fixing is known. It is clear that good fixability can be obtained by using a toner that satisfies both the characteristics that the glass transition temperature is 45 to 65 ° C. and the outflow start temperature is 90 to 115 ° C. became. When the glass transition temperature is lower than 45 ° C., offset may occur during fixing. Conversely, when the glass transition temperature is higher than 65 ° C., sufficient fixing property cannot be obtained, and the image is easily peeled off from the transfer paper. There is. If the outflow start temperature is lower than 90 ° C, offset may occur during fixing. Conversely, if it is higher than 115 ° C, sufficient fixability cannot be obtained, and the image tends to peel off from the transfer paper. There is.

  The method for measuring the glass transition point (Tg) will be outlined. As an apparatus for measuring Tg, a TG-DSC system TAS-100 manufactured by Rigaku Corporation was used. First, about 10 mg of a sample is placed in an aluminum sample container, which is placed on a holder unit and set in an electric furnace. First, after heating from room temperature to 150 ° C. at a temperature rising rate of 10 ° C./min, the sample was allowed to stand at 150 ° C. for 10 min, the sample was cooled to room temperature and left for 10 min, and the temperature rising rate was again increased to 150 ° C. under a nitrogen atmosphere. DSC measurement was performed by heating at min. Tg was calculated from the contact point between the tangent line of the endothermic curve near the Tg and the base line using the analysis system in the TAS-100 system.

The toner flow start temperature can be measured using a flow tester. An example of a flow tester is an elevated flow tester CFT500D manufactured by Shimadzu Corporation. The flow curve of this flow tester becomes the data shown in FIGS. 10A and 10B, from which each temperature can be read. In the figure, Tfb is the outflow start temperature, and the melting temperature in the 1/2 method is the T1 / 2 temperature.
Measurement conditions: Load: 5 kg / cm ² , Temperature rising rate: 3.0 ° C./min, Die diameter 1.00 mm, Die length 10.0 mm

  As the binder resin used in the toner of the present invention, those having the following composition can be used as long as the toner characteristics of the present invention are satisfied. For example, homopolymers of styrene such as polyester, polystyrene, poly p-chlorostyrene, polyvinyltoluene and the like; and styrene-p-chlorostyrene copolymers, styrene-propylene copolymers, styrene-vinyltoluene copolymers. Styrene-vinyl naphthalene 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, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, Styrene-vinyl ethyl acetate Copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester A styrene copolymer such as a copolymer.

  The following resins can also be used in combination: polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyacrylic acid resin, rosin , Modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax and the like. Among these, a polyester resin is particularly preferable in order to obtain sufficient fixability. The polyester resin is obtained by condensation polymerization of alcohol and carboxylic acid, and the alcohol used is polyethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4- Diols such as butanediol, neopentyl glycol, 1,4-butenediol, 1,4-bis (hydroxymethyl) cyclohexane, bisphenol A, hydrogenated bisphenol A, polyexethylenated bisphenol A, polyoxypropylenated bisphenol A And the like, etherified bisphenols such as divalent alcohols in which these are substituted with a saturated or unsaturated hydrocarbon group having 3 to 22 carbon atoms, and other divalent alcohols alone.

  Examples of the carboxylic acid used to obtain the polyester resin include maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, Adipic acid, sebacic acid, malonic acid, divalent organic acid monomers in which these are substituted with a saturated or unsaturated hydrocarbon group having 3 to 22 carbon atoms, acid anhydrides thereof, lower alkyl esters and linolenic acid Dimers and other divalent organic acid monomers can be mentioned.

  In order to obtain a polyester resin to be used as a binder resin, it is also preferable to use not only a polymer with only the above bifunctional monomer but also a polymer containing a component with a trifunctional or higher polyfunctional monomer. It is. Examples of the polyhydric alcohol monomer having three or more valences that are such polyfunctional monomers include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sarbitane, pentaesitol, dipenta. Esitol, tripentaerythritol, sucrose, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol , Trimethylolethane, trimethylolpropane, 1.3.5-trihydroxymethylbenzene, and others.

  Examples of the trivalent or higher polyvalent carboxylic acid monomer include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2 -Methylenecarboxypropane, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, embol trimer acid, acid anhydrides thereof, and the like.

  Further, the toner of the present invention may contain a release agent for the purpose of improving the releasability of the toner on the surface of the fixing belt at the time of fixing. As the release agent, all known ones can be used, and in particular, defree fatty acid type carnauba wax, montan wax, oxidized rice wax, and ester wax can be used alone or in combination. The carnauba wax is preferably a microcrystalline one, having an acid value of 5 or less and a particle size of 1 μm or less when dispersed in a toner binder. The montan wax generally refers to a montan wax refined from minerals, and like a carnauba wax, it is microcrystalline and preferably has an acid value of 5 to 14. The oxidized rice wax is obtained by air-oxidizing rice bran wax, and the acid value is preferably 10-30. When the acid value of each wax is less than the respective range, the low temperature fixing temperature rises and the low temperature fixing becomes insufficient. On the contrary, when the acid value exceeds each range, the cold offset temperature rises and the low-temperature fixing becomes insufficient. The added amount of the wax is 1 to 15 parts by weight, preferably 3 to 10 parts by weight with respect to 100 parts by weight of the binder resin. If it is less than 1 part by weight, the releasing effect is thin and the desired effect is difficult to obtain. On the other hand, when the amount exceeds 15 parts by weight, there is a problem that the spent on the carrier becomes remarkable.

  Further, for the purpose of imparting charge to the toner, a charge control agent can be contained. Any conventionally known charge control agent can be used. Examples of positive charge control agents include nigrosine, basic dyes, basic dye lake pigments, quaternary ammonium salt compounds, and the like. Negative charge control agents include metal salts of monoazo dyes, salicylic acid, naphthoic acid, dyes, and the like. And metal complexes of carboxylic acids. The amount of the polarity control agent used is determined by the toner production method including the type of binder resin, the presence or absence of additives used as necessary, and the dispersion method, and is not limited uniquely. Is used in an amount of 0.01 to 8 parts by weight, preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the binder resin. If it is less than 0.01 part by weight, the effect is small with respect to the fluctuation of the charge amount Q / M at the time of environmental change.

  In addition, as the metal-containing monoazo dye used, a chromium-containing monoazo dye, a cobalt-containing monoazo dye, and an iron-containing monoazo dye can be used alone or in combination. By adding these, the rising of the charge amount Q / M in the developer (time until saturation) becomes more excellent. The amount used is determined by the toner production method including the type of binder resin, the presence or absence of additives used as necessary, and the dispersion method as in the case of the polar control agent, and is uniquely limited. However, it is used in the range of 0.1 to 10 parts by weight, preferably 1 to 7 parts by weight with respect to 100 parts by weight of the binder resin. If the amount is less than 0.1 parts by weight, the effect is small, and if the amount exceeds 10 parts by weight, defects such as a decrease in the saturation level of the charge amount occur.

  In addition, it is particularly preferable to use a metal salt of a salicylic acid derivative for the color toner, but if necessary, a transparent or white substance that does not impair the color tone of the color toner is added to stabilize the chargeability of the toner. Can be granted. Specifically, organic boron salts, fluorine-containing quaternary ammonium salts, calixarene compounds, and the like are used, but are not limited thereto.

  Furthermore, the toner of the present invention further contains a magnetic material and can be used as a magnetic toner. Magnetic materials contained in the magnetic toner of the present invention include iron oxides such as magnetite, hematite, and ferrite, metals such as iron, cobalt, and nickel, or aluminum, cobalt, copper, lead, magnesium, tin, and zinc of these metals. And alloys of metals such as antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, vanadium, and mixtures thereof.

  These ferromagnetic materials preferably have an average particle size of about 0.1 to 2 μm. The amount of the ferromagnetic material contained in the toner is about 20 to 200 parts by weight, particularly preferably 100 parts by weight of the resin component, based on 100 parts by weight of the resin component. 40 to 150 parts by weight per part.

  As the colorant, all known colorants can be used. As the black colorant, for example, carbon black, aniline black, furnace black, lamp black and the like can be used. Examples of cyan colorants include phthalocyanine blue, methylene blue, Victoria blue, methyl violet, aniline blue, and ultramarine blue. As the magenta colorant, for example, rhodamine 6G lake, dimethylquinacridone, watching red, rose bengal, rhodamine B, alizarin lake and the like can be used. Examples of yellow colorants include chrome yellow, benzidine yellow, hansa yellow, naphthol yellow, molybdenum orange, quinoline yellow, and tartrazine. As the colorant used in the toner of the present invention, dyes and pigments capable of obtaining toners of yellow, magenta, cyan and black colors can be used. For example, carbon black, lamp black, ultramarine blue, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa Yellow G, Rogmin 6G, lake, chaco oil blue, chrome yellow, quinacridone, benzidine yellow, rose bengal, triallylmethane dye, etc. Any conventionally known dyes and pigments such as dyes and pigments can be used alone or in combination.

  Further, as an external additive, for the purpose of improving the fluidity of the toner, a hydrophobic silica, titanium oxide, alumina, or the like, and a fatty acid metal salt or polyvinylidene fluoride may be added as necessary.

  Further, when the toner of the present invention is used as a two-component developer, all known carriers can be used. For example, magnetic powder such as iron powder, ferrite powder, nickel powder, glass, and the like. Examples thereof include beads and the like and those whose surfaces are treated with a resin or the like.

  Examples of the resin powder that can be coated on the carrier in the present invention include a styrene-acrylic copolymer, a silicone resin, a maleic acid resin, a fluorine resin, and a polyester resin epoxy resin. In the case of a styrene-acrylic copolymer, those having a styrene content of 30 to 90% by weight are preferred. In this case, when the styrene content is less than 30% by weight, the development characteristics are low, and when it exceeds 90% by weight, the coating film becomes hard and easily peeled, and the life of the carrier is shortened. Moreover, the resin coating of the carrier in the present invention may contain an adhesion-imparting agent, a curing agent, a lubricant, a conductive material, a charge control agent, and the like in addition to the resin.

  In the present invention, the carrier core particles coated with the silicone resin may be conventionally known particles such as ferromagnetic metals such as iron, cobalt and nickel; alloys and compounds such as magnetite, hematite and ferrite; and glass beads. It is done. The average particle diameter of these core particles is usually 10 to 1000 μm, preferably 30 to 500 μm. In addition, the usage-amount of a silicone resin is 1 to 10 weight% normally with respect to a carrier core particle.

  The silicone resin used in the present invention may be any conventionally known silicone resin. For example, commercially available KR261, KR271, KR271, KR272, KR275, KR280, KR282, KR285 manufactured by Shin-Etsu Silicone. , KR251, KR155, KR220, KR201, KR204, KR205, KR206, SA-4, ES1001, ES1001N, ES1002T, KR3093, SR2100, SR2101, SR2107, SR2110, SR2108, SR2109, SR2115, SR2115, SR2400, SR2410 SR2411, SH805, SH806A, SH840, etc. are used. As a method for forming the silicone resin layer, a silicone resin may be applied to the surface of the carrier core particles by means of a spraying method, a dipping method or the like, as in the past.

  The toner suitably used in the image forming apparatus of the present invention includes a toner material liquid in which at least a polyester prepolymer having a functional group containing a nitrogen atom, a polyester, a colorant, and a release agent are dispersed in an organic solvent. A toner obtained by crosslinking and / or elongation reaction in an aqueous solvent. Hereinafter, the constituent material and the manufacturing method of the toner will be described.

  The polyester is obtained by a polycondensation reaction between a polyhydric alcohol compound and a polycarboxylic acid compound. Examples of the polyhydric alcohol compound (PO) include dihydric alcohol (DIO) and trihydric or higher polyhydric alcohol (TO). (DIO) alone or a mixture of (DIO) and a small amount of (TO) preferable. Examples of the dihydric alcohol (DIO) include alkylene glycol (ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, etc.); alkylene ether glycol (diethylene glycol) , Triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc.); alicyclic diols (1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.); bisphenols (bisphenol A, bisphenol) F, bisphenol S, etc.); alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adduct of the above alicyclic diol; Alkylene oxide bisphenol (ethylene oxide, propylene oxide, butylene oxide, etc.), etc. adducts. Among them, preferred are alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols, and particularly preferred are alkylene oxide adducts of bisphenols and alkylene glycols having 2 to 12 carbon atoms. It is a combined use. The trihydric or higher polyhydric alcohol (TO) 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 polyvalent carboxylic acid (PC) include divalent carboxylic acid (DIC) and trivalent or higher polyvalent carboxylic acid (TC). (DIC) alone and (DIC) with a small amount of (TC) Mixtures are preferred. Divalent carboxylic acids (DIC) include alkylene dicarboxylic acids (succinic acid, adipic acid, sebacic acid, etc.); alkenylene dicarboxylic acids (maleic acid, fumaric acid, etc.); aromatic dicarboxylic acids (phthalic acid, isophthalic acid, terephthalic acid) And naphthalenedicarboxylic acid). Of these, preferred are alkenylene dicarboxylic acids having 4 to 20 carbon atoms and aromatic dicarboxylic acids having 8 to 20 carbon atoms. Examples of the trivalent or higher polyvalent carboxylic acid (TC) include aromatic polycarboxylic acids having 9 to 20 carbon atoms (such as trimellitic acid and pyromellitic acid). In addition, as polyhydric carboxylic acid (PC), you may make it react with polyhydric alcohol (PO) using the above-mentioned acid anhydride or lower alkyl ester (Methyl ester, ethyl ester, isopropyl ester, etc.).

  The ratio of the polyhydric alcohol (PO) to the polycarboxylic acid (PC) is usually 2/1 to 1/1, preferably as the equivalent ratio [OH] / [COOH] of the hydroxyl group [OH] and the carboxyl group [COOH]. Is 1.5 / 1 to 1/1, more preferably 1.3 / 1 to 1.02 / 1.

  The polycondensation reaction between a polyhydric alcohol (PO) and a polycarboxylic acid (PC) is carried out in the presence of a known esterification catalyst such as tetrabutoxytitanate or dibutyltin oxide, and heated to 150 to 280 ° C. while reducing the pressure as necessary. The produced water is distilled off to obtain a polyester having a hydroxyl group. The hydroxyl value of the polyester is preferably 5 or more, and the acid value of the polyester is usually 1 to 30, preferably 5 to 20. By giving an acid value, the toner tends to be negatively charged, and further, when fixing to a recording paper, the affinity between the recording paper and the toner is good and the low-temperature fixing property is improved. However, when the acid value exceeds 30, there is a tendency to deteriorate with respect to the stability of charging, particularly environmental fluctuation.

  The weight average molecular weight is 10,000 to 400,000, preferably 20,000 to 200,000. A weight average molecular weight of less than 10,000 is not preferable because offset resistance deteriorates. On the other hand, if it exceeds 400,000, the low-temperature fixability is deteriorated.

  In addition to the unmodified polyester obtained by the above polycondensation reaction, the polyester preferably contains a urea-modified polyester. The urea-modified polyester is obtained by reacting a terminal carboxyl group or hydroxyl group of the polyester obtained by the above polycondensation reaction with a polyvalent isocyanate compound (PIC) to obtain a polyester prepolymer (A) having an isocyanate group. It is obtained by cross-linking and / or extending the molecular chain by the reaction of the amine with amines.

  Examples of the polyvalent isocyanate compound (PIC) include aliphatic polyisocyanates (tetramethylene diisocyanate, hexamethylene diisocyanate, 2,6-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.); isocyanates; Those blocked with caprolactam or the like; and combinations of two or more of these.

  The ratio of the polyvalent isocyanate compound (PIC) is usually 5/1 to 1/1, preferably as an equivalent ratio [NCO] / [OH] of the isocyanate group [NCO] and the hydroxyl group [OH] of the polyester having a hydroxyl group. 4/1 to 1.2 / 1, more preferably 2.5 / 1 to 1.5 / 1. When [NCO] / [OH] exceeds 5, low-temperature fixability deteriorates. When the molar ratio of [NCO] is less than 1, when a urea-modified polyester is used, the urea content in the ester is lowered and hot offset resistance is deteriorated.

  The content of the polyisocyanate compound (PIC) component in the polyester prepolymer (A) having an isocyanate group is usually 0.5 to 40 wt%, preferably 1 to 30 wt%, more preferably 2 to 20 wt%. . If it is less than 0.5 wt%, the hot offset resistance deteriorates, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability. On the other hand, if it exceeds 40 wt%, the low-temperature fixability deteriorates.

  The number of isocyanate groups contained per molecule in the polyester prepolymer (A) having an isocyanate group is usually 1 or more, preferably 1.5 to 3 on average, more preferably 1.8 to 2 on average. Five. If it is less than 1 per molecule, the molecular weight of the urea-modified polyester will be low, and the hot offset resistance will deteriorate.

  Next, as amines (B) to be reacted with the polyester prepolymer (A), a divalent amine compound (B1), a trivalent or higher polyvalent amine compound (B2), an amino alcohol (B3), an amino mercaptan (B4) ), Amino acid (B5), and amino acid block of B1 to B5 (B6).

  Examples of the divalent amine compound (B1) include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4′-diaminodiphenylmethane, etc.); alicyclic diamines (4,4′-diamino-3,3′-dimethyldicyclohexyl). Methane, diamine cyclohexane, isophorone diamine, etc.); and aliphatic diamines (ethylene diamine, tetramethylene diamine, hexamethylene diamine, etc.) and the like.

  Examples of the trivalent or higher polyvalent amine compound (B2) include diethylenetriamine and triethylenetetramine. Examples of amino alcohol (B3) include ethanolamine and hydroxyethylaniline. Examples of amino mercaptan (B4) include aminoethyl mercaptan and aminopropyl mercaptan.

  Examples of the amino acid (B5) include aminopropionic acid and aminocaproic acid. Examples of the compound (B6) obtained by blocking the amino group of B1 to B5 include ketimine compounds and oxazolidine compounds obtained from the amines of B1 to B5 and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.). Among these amines (B), preferred are B1 and a mixture of B1 and a small amount of B2.

  The ratio of amines (B) is equivalent to the equivalent ratio [NCO] / [NHx] of isocyanate groups [NCO] in the polyester prepolymer (A) having isocyanate groups and amino groups [NHx] in amines (B). Is usually 1/2 to 2/1, preferably 1.5 / 1 to 1 / 1.5, more preferably 1.2 / 1 to 1 / 1.2. When [NCO] / [NHx] is 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.

  The urea-modified polyester may contain a urethane bond together with a urea bond. The molar ratio of the urea bond content to the urethane bond content is usually 100/0 to 10/90, preferably 80/20 to 20/80, and more preferably 60/40 to 30/70. When the molar ratio of the urea bond is less than 10%, the hot offset resistance is deteriorated.

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

  When reacting (PIC) and when reacting (A) and (B), a solvent may be used if necessary. Usable solvents include aromatic solvents (toluene, xylene, etc.); ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.); esters (ethyl acetate, etc.); amides (dimethylformamide, dimethylacetamide, etc.) and ethers And those inert to isocyanates (PIC), such as tetrahydrofuran (such as tetrahydrofuran).

  In addition, in the crosslinking and / or extension reaction between the polyester prepolymer (A) and the amines (B), a reaction terminator can be used as necessary to adjust the molecular weight of the resulting urea-modified polyester. Examples of the reaction terminator include monoamines (diethylamine, dibutylamine, butylamine, laurylamine, etc.), and those obtained by blocking them (ketimine compounds).

  The weight average molecular weight of the urea-modified polyester is usually 10,000 or more, preferably 20,000 to 10,000,000, and more preferably 30,000 to 1,000,000. If it is less than 10,000, the hot offset resistance deteriorates. The number average molecular weight of the urea-modified polyester is not particularly limited when the above-mentioned unmodified polyester is used, and may be a number average molecular weight that can be easily obtained to obtain the weight average molecular weight. When the urea-modified polyester is used alone, the number average molecular weight is usually 2000 to 15000, preferably 2000 to 10,000, and more preferably 2000 to 8000. When it exceeds 20000, the low-temperature fixability and the glossiness when used in a color apparatus are deteriorated.

  By using the unmodified polyester and the urea-modified polyester in combination, the low-temperature fixability and the gloss when used in the color image forming apparatus 100 are improved. Therefore, it is preferable to use the urea-modified polyester alone. The unmodified polyester may include a polyester modified with a chemical bond other than a urea bond.

  The unmodified polyester and the urea-modified polyester are preferably at least partially compatible with each other in terms of low-temperature fixability and hot offset resistance. Therefore, it is preferable that the unmodified polyester and the urea-modified polyester have a similar composition.

  The weight ratio of unmodified polyester to urea-modified polyester is usually 20/80 to 95/5, preferably 70/30 to 95/5, more preferably 75/25 to 95/5, particularly preferably 80 /. 20-93 / 7. When the weight ratio of the urea-modified polyester is less than 5%, the hot offset resistance is deteriorated, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability.

  The glass transition point (Tg) of the binder resin containing unmodified polyester and urea-modified polyester is usually 45 to 65 ° C, preferably 45 to 60 ° C. If it is less than 45 ° C., the heat resistance of the toner deteriorates, and if it exceeds 65 ° C., the low-temperature fixability becomes insufficient.

  In addition, since the urea-modified polyester is likely to be present on the surface of the obtained toner base particles, the heat-resistant storage stability tends to be good even when the glass transition point is low as compared with known polyester-based toners.

  As the colorant, all known dyes and pigments can be used. For example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, ocher , Yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), permanent yellow (NCG), Vulcan fast yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL, Isoindolinone Yellow, Bengala, Red Dan, Lead Zhu, Cadmium Red, Cadmium Mercury Red, Antimon Zhu, Permanent Red 4R, Para Red, Phi Sared, Parachlor Ortoni Roaniline 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, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thioindigo red B, thioindigo maroon, oil red, quinacridone red, pyrazolone , Polyazo Red, Chrome Vermillion, Benzidine Orange, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal Free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), Indigo, Ultramarine Blue, Bitumen, Anthraquinone Blue, Fast Violet B, Methyl Violet Lake, Cobalt Purple, Manganese Purple, Dioxane Violet, Anthraquinone Violet, Chrome Green, Zinc Green, Chrome Oxide, Pyridian, Emerald Green, Pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite Green Lake, Fu Talocyanine green, anthraquinone green, titanium oxide, zinc white, litbon and mixtures thereof can be used. The content of the colorant is usually 1 to 15% by weight, preferably 3 to 10% by weight, based on the toner.

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

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

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

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

The charge control agent and the release agent can be melt-kneaded together with the master batch and the binder resin, and of course, they may be added when dissolved and dispersed in the organic solvent.
Inorganic fine particles are preferably used as an external additive for assisting the fluidity, developability and chargeability of the toner particles. The primary particle diameter of the inorganic fine particles is preferably 5 × ¹⁰ -3 ~2μm, it is particularly preferably 5 × ¹⁰ -3 ~0.5μm. Moreover, it is preferable that the specific surface area by BET method is 20-500 m < ² > / g. The use ratio of the inorganic fine particles is preferably 0.01 to 5 wt% of the toner, and particularly preferably 0.01 to 2.0 wt%.

Specific examples of the inorganic fine particles include, for example, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, quartz sand, clay, mica, wollastonite, diatomaceous earth. Examples include soil, chromium oxide, cerium oxide, bengara, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride. Among these, as the fluidity imparting agent, it is preferable to use hydrophobic silica fine particles and hydrophobic titanium oxide fine particles in combination. In particular, when stirring and mixing are performed using particles having an average particle diameter of 5 × 10 ⁻² μm or less, the electrostatic force and van der Waals force with the toner are remarkably improved. Even when stirring and mixing inside the developing device is performed to obtain a good image quality that does not cause the release of fluidity from the toner and does not generate firefly, etc., and further reduces the residual toner. It is done.

  Titanium oxide fine particles are excellent in environmental stability and image density stability, but have a tendency to deteriorate the charge rise characteristics. Therefore, if the amount of titanium oxide fine particles added is larger than the amount of silica fine particles added, this side effect is affected. It can be considered large.

  However, when the added amount of the hydrophobic silica fine particles and the hydrophobic titanium oxide fine particles is in the range of 0.3 to 1.5 wt%, the charge rising characteristics are not greatly impaired, and the desired charge rising characteristics can be obtained, that is, repeated copying. Stable image quality can be obtained even if

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

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

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

  Further, by using a surfactant having a fluoroalkyl group, the effect can be obtained in a very small amount. Preferred anionic surfactants having a fluoroalkyl group include fluoroalkyl carboxylic acids having 2 to 10 carbon atoms and metal salts thereof, disodium perfluorooctanesulfonyl glutamate, 3- [ω-fluoroalkyl (C6-C11 ) Oxy] -1-alkyl (C3-C4) sodium sulfonate, 3- [ω-fluoroalkanoyl (C6-C8) -N-ethylamino] -1-propanesulfonic acid sodium, fluoroalkyl (C11-C20) carvone Acids and metal salts, perfluoroalkylcarboxylic acids (C7 to C13) and metal salts thereof, perfluoroalkyl (C4 to C12) sulfonic acids and metal salts thereof, perfluorooctanesulfonic acid diethanolamide, N-propyl-N- ( 2-Hydroxyethyl) Perful Olooctanesulfonamide, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt, perfluoroalkyl (C6-C10) -N-ethylsulfonylglycine salt, monoperfluoroalkyl (C6-C16) ethyl phosphate, etc. Can be mentioned.

  Product names include Surflon S-111, S-112, S-113 (Asahi Glass Co., Ltd.), Florard FC-93, FC-95, FC-98, FC-129 (Sumitomo 3M Co., Ltd.), Unidyne DS-101. DS-102 (manufactured by Daikin Industries, Ltd.), Megafac F-110, F-120, F-113, F-191, F-812, F-833 (manufactured by Dainippon Ink, Inc.), Xtop EF-102, 103, 104, 105, 112, 123A, 123B, 306A, 501, 201, 204 (manufactured by Tochem Products), and Fgentent F-100, F150 (manufactured by Neos).

  Moreover, as the cationic surfactant, aliphatic quaternary ammonium such as aliphatic primary, secondary or secondary amic acid, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt which has a right fluoroalkyl group is used. Salts, benzalkonium salts, benzethonium chloride, pyridinium salts, imidazolinium salts, trade names include Surflon S-121 (Asahi Glass Co., Ltd.), Florard FC-135 (Sumitomo 3M Co., Ltd.), Unidyne DS-202 (Daikin Industries) Smoke), MegaFuck F-150, F-824 (Dainippon Ink Co., Ltd.), Xtop EF-132 (Tochem Products), Footage F-300 (Neos), and the like.

  The resin fine particles are added to stabilize the toner base particles formed in the aqueous medium. For this reason, it is preferable to add so that the coverage existing on the surface of the toner base particles is in the range of 10 to 90%. For example, polymethyl methacrylate fine particles 1 μm and 3 μm, polystyrene fine particles 0.5 μm and 2 μm, poly (styrene-acrylonitrile) fine particles 1 μm, trade names are PB-200H (manufactured by Kao), SGP (manufactured by Soken), Techno Examples include polymer SB (manufactured by Sekisui Chemical Co., Ltd.), SGP-3G (manufactured by Sokensha), and micropearl (manufactured by Sekisui Fine Chemical Co., Ltd.).

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

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

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

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

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

1 is a schematic diagram illustrating a configuration of an intermediate transfer type image forming apparatus. FIG. 2 is a schematic view showing a process cartridge in the image forming apparatus of FIG. 1. FIG. 2 is a conceptual diagram showing an aspect during monochrome printing in the image forming apparatus of FIG. 1. FIG. 2 is a conceptual diagram illustrating an aspect during color printing in the image forming apparatus of FIG. 1. It is the schematic of the image forming apparatus of another structure. FIG. 6 is a schematic view showing a process cartridge in the image forming apparatus of FIG. 5. It is a flowchart regarding the saving station switching in monochrome printing and color printing when entering printing. FIG. 6 is a toner shape schematic diagram for explaining a shape factor SF-1. FIG. 6 is a toner shape schematic diagram for explaining a shape factor SF-2. It is a flow curve in the flow tester which measures the outflow start temperature of a toner. It is a conceptual diagram explaining the movement of the toner in the conventional black station.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging roller 4 Developing apparatus 6 Intermediate transfer belt 7 Cleaning blade 9 Brush roller 10 Waste toner collection coil 11 Charging cleaner roller 12 Charging roller pressure spring 13 Charging cleaner roller pressure spring 14 Lubricant 15 Lubricant pressure spring 16 Lubricant application blade 61 Transfer roller 90 Process cartridge

Claims (4)

  A color image forming apparatus having a plurality of image forming stations each having an image carrier, a developing device, and a structure for collecting waste toner from the image carrier. In the black image forming station, the collected waste toner is supplied to a developing device. A return mechanism is provided, and when performing monochrome printing, image formation is performed only at the black image forming station, and residual toner on the image carrier is returned to the developing device to perform color printing. In this case, the primary transfer means for the black image forming station is retracted away from the corresponding image carrier, and the image carrier and the intermediate transfer means or the recording medium are separated from each other. A color image forming apparatus characterized by forming.   A color image forming apparatus having a plurality of image forming stations each having an image carrier, a developing device, and a structure for collecting waste toner from the image carrier. In the black image forming station, the collected waste toner is supplied to a developing device. A return mechanism is provided, and when performing monochrome printing, image formation is performed only at the black image forming station, and residual toner on the image carrier is returned to the developing device to perform color printing. In this case, the image carrier of the black image forming station is retracted and separated in a direction away from the intermediate transfer unit or the recording medium, and an image is formed only by another image forming station.   3. The color image forming apparatus according to claim 1, wherein among the plurality of image forming stations, the black image forming station is arranged at a position other than the most upstream side in the moving direction of the intermediate transfer unit or the recording medium. .   3. The color image forming apparatus according to claim 1, wherein the black image forming station is configured as a process cartridge in which at least an image carrier and a cleaning unit are integrated.

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