JPH0557586B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an electrostatic image developer used for developing an electrostatic latent image formed in electrophotography, electrostatic recording, electrostatic printing, etc., and this electrostatic image developer. Electrostatic image developing method for developing an electrostatic latent image formed on the surface of a photoreceptor made of an organic photoconductive semiconductor using an image developer, and these electrostatic image developers and electrostatic image developing method The present invention relates to an image forming method for forming an image using an electrostatic image developer and an electrostatic image developer suitable for developing a negative electrostatic latent image formed on the surface of a photoreceptor made of an organic photoconductive semiconductor. The present invention relates to an electrostatic image developing method and an image forming method. [Background of the Invention] Generally, in electrophotography, a photoreceptor having a photosensitive layer made of a photoconductive material is given a uniform electrostatic charge, and then image exposure is performed to create an electrostatic latent on the surface of the photoreceptor. An image is formed, and this electrostatic latent image is developed with a developer to form a toner image. After the obtained toner image is transferred to a transfer material such as paper,
A copy image is formed by fixing by heating or pressure. Examples of the photoconductive material used to form the photosensitive layer of the photoreceptor include inorganic photoconductive materials such as selenium, zinc oxide, and cadmium sulfide, and organic photoconductive materials made of high molecular compounds or low molecular weight compounds such as polyvinyl carbazole. There are known materials such as carbonaceous materials. However, although photoreceptors having photosensitive layers formed from these photoconductive materials have one advantage in forming electrostatic latent images, they also have drawbacks specific to various photoreceptors. have. For example, in a photoreceptor having a photosensitive layer formed of selenium, the photosensitive layer easily crystallizes due to heat or exposure to metal compounds contained in the developer or transfer material, degrading its properties and causing electrostatic potential. There are problems in that the potential of the image decreases, resulting in a decrease in image density or partial image blanking.
In addition, under high humidity environmental conditions, the photoconductivity of the photosensitive layer decreases and static charges remain in the non-image areas of the photoreceptor, resulting in fogging and making it difficult to obtain clear images. First, under high humidity environmental conditions, good images cannot be formed many times and durability is low. Additionally, photoreceptors having a photosensitive layer formed of cadmium sulfide or a photoreceptor having a photosensitive layer formed of zinc oxide typically have a photoconductive material, ie, cadmium sulfide or zinc oxide, dispersed in a binder resin. A photosensitive layer is formed, but it is quite difficult to uniformly disperse such a photoconductive material in the form of fine particles in a binder resin, and as a result, the resulting photoreceptor has low sensitivity and is unsuitable for high-speed copying. In addition, the photosensitive layer tends to deteriorate early in the corona charging process or exposure process that is normally used to form an electrostatic latent image, and therefore it is difficult to maintain a good image quality over a long period of time. Furthermore, under high-humidity environmental conditions, moisture changes the properties of the photosensitive layer, making it impossible to obtain the desired electrostatic latent image potential, resulting in low image density. There is a problem. On the other hand, organic photoreceptors having a photosensitive layer formed from a polymeric photoconductive material typified by polyvinylcarbazole have good film-forming properties and can be manufactured at low cost. It has been attracting attention in recent years due to its advantages such as non-toxicity, but on the other hand, it has low sensitivity and is prone to early deterioration during the corona charging process or exposure process, resulting in poor durability. Since the sensitivity or charge retention ability tends to change, it is still inferior to photoreceptors having a photosensitive layer made of an inorganic photoconductive material, and the development of a high-performance photoconductive material is desired. On the other hand, in order to overcome the above problems, in recent years,
It has been proposed to use low molecular weight organic photoconductive materials. Since low molecular weight organic photoconductive materials have good dispersibility in general binder resins, the resulting photosensitive layer has the organic photoconductive materials uniformly dispersed in the form of fine particles, resulting in improved sensitivity. By forming the photosensitive layer by dispersing an organic photoconductive material in a binder resin, it is possible to obtain a photoreceptor with relatively high
Film-forming properties are improved, and photoreceptors can therefore be manufactured with high productivity.In addition, there are many types of low-molecular-weight photoconductive materials that can be used, and therefore, it is possible to use appropriately selected low-molecular-weight photoconductive materials. By using the photoreceptor, it is possible to obtain a photoreceptor having better performance than conventional ones. Thus, an organic photoreceptor having a photosensitive layer formed of a low molecular weight organic photoconductive material is more preferable than conventional photoreceptors. However, since organic photoconductive materials usually exhibit photoconductivity through the movement of positive charges, it is difficult to form photoconductive materials on the surface of an organic photoreceptor that has a photosensitive layer formed from the organic photoconductive material. The polarity of the electrostatic latent image is preferably negative. In order to develop a negative electrostatic latent image, it is necessary to use a developer containing positively charged toner. However, in the conventionally widely used photoreceptor having a photosensitive layer made of selenium, etc., the polarity of the electrostatic latent image formed on the surface is positive, so it is difficult to develop the electrostatic latent image. A developer containing a negatively chargeable toner is used, and therefore considerable research and development has been done on a developer containing a negatively chargeable toner. Research and development of developers containing toner is still lagging behind, and the reality is that a developer containing a sufficiently positively charged toner has not been obtained. On the other hand, wet developing methods and dry developing methods are known as methods for developing electrostatic latent images. The former wet development method uses a liquid developer, which has the problem of emitting a bad odor, and also requires high energy to dry the transfer material, making high-speed copying difficult. The latter dry developing method does not have such problems and can be preferably used as a developing method for electrostatic latent images. The developer used in the dry development method is a so-called one-component developer consisting only of a magnetic toner containing a magnetic substance, and a so-called two-component developer consisting of a non-magnetic toner that does not contain a magnetic substance and a magnetic carrier. A developer is known. The former one-component developer consists only of magnetic toner and does not have a carrier, so there is some frictional electrification caused by the toners and the height of the toner and the developing sleeve or developer layer placed in the developing device is controlled. The toner is charged by frictional charging with the regulation blade, etc., and as a result, both positively charged toner and negatively charged toner exist.
Moreover, since the amount of triboelectric charge is small, there is basically a problem that development tends to be unstable. Specifically, for example, toner may adhere to non-image areas on the photoreceptor, causing fog on the final fixed image, or
Alternatively, there is a problem that an insufficient amount of toner adheres to the image area on the photoreceptor, resulting in a low density of the final fixed image. In addition, the magnetic material used in magnetic toner usually has hydrophilic properties, and since this hydrophilic magnetic material is often contained in an exposed state on the surface of toner particles, the toner becomes triboelectrically charged due to moisture. Charge tends to leak, and in a high-humidity atmosphere, the electrostatic transfer to the transfer paper normally used as a transfer material becomes defective during the transfer process, resulting in a low toner transfer rate to the transfer paper. As a result, there are problems in that the density of the final fixed image decreases and image blanking occurs. In addition, since the magnetic material used in magnetic toner usually has negative chargeability, it is difficult to positively charge the magnetic toner with an appropriate amount of charge.
Therefore, there is a large proportion of toner of opposite polarity, which results in a lower density in the final fixed image, and also causes problems such as unevenness and missing images. On the other hand, the latter two-component developer is composed of toner and a carrier, and the carrier has the function of charging the toner to a desired polarity, so it is possible to charge the toner with an appropriate polarity and an appropriate charge. It is possible to impart a triboelectric charge depending on the amount, and it is possible to obtain a developer having much superior triboelectric chargeability compared to the one-component developer described above. Also,
By selecting a carrier having desired characteristics, it is possible to control the amount of charge on the toner to a considerable extent. However, in order to obtain a good final fixed image, it is not enough that the developer has good triboelectric chargeability, and particles of the developer to which triboelectric charge has been applied do not aggregate in the developing device. It is necessary that the film be transported to the developing space in good condition without any damage. For example, in the magnetic brush development method, a developer that has been given a triboelectric charge by being stirred in a developing device is supported on the developing sleeve in the form of a thin layer arranged in a uniform brush shape. It is necessary for the developer layer having the same shape to be stably transported to the development space while retaining its shape. For example, in a one-component developer, since it consists only of magnetic toner and does not have a carrier, the magnetic toner has strong magnetic cohesive force and electrostatic cohesive force. There is a problem in that the fluidity of the developer is reduced, and as a result, it is difficult to carry the magnetic toner on the developing sleeve in the form of a thin layer arranged in a uniform brush shape. In addition, since the magnetic toner tends to form agglomerates, frictional electrification between the magnetic toners or between the magnetic toner and the wall, regulating blade, developing sleeve, etc. inside the developing device is not achieved properly. As a result, there is a problem that the final fixed image becomes unclear with a lot of fog. Furthermore, for example, in a two-component developer, if the toner tends to aggregate and form clumps due to electrostatic cohesive force, it becomes difficult to disperse the toner particles in the carrier particles at a uniform concentration.
As a result, the triboelectricity between the toner and the carrier decreases, and the proportion of toner with low triboelectricity increases.In the developing process, toner adheres to non-image areas on the photoreceptor, causing fog in the final fixed image. death,
In addition, there is a large amount of weakly charged toner, and the electrostatic adhesion force between the toner and the carrier is small. Therefore, in the magnetic brush development method, the toner particles attached to the carrier particles are rotated by magnetic force. When conveyed to the developing space, the toner particles scatter due to the centrifugal force caused by the rotation of the carrier particles, and as a result, they contaminate various devices such as the charger and exposure optical system installed in the copying machine, and the final fixation is interrupted. There is a problem that image defects such as image unevenness and image blanking occur in the image. However, in conventional negatively charged toners, fine silica particles having a smaller diameter than the toner particles are mixed with the toner particles to attach the fine silica particles to the surface of the toner particles, thereby preventing the toner from clumping. This is done to obtain high liquidity. However, conventionally used silica fine particles have strong negative chargeability, so in order to obtain a positively chargeable toner, if silica fine particles are mixed with the toner and attached to the surface of the toner particles, the resulting toner will be negatively charged. As a result, the negative electrostatic latent image formed on the photoreceptor becomes of the same polarity as the negative electrostatic latent image, and there is a problem that electrostatic development cannot be carried out. The following techniques have been disclosed as techniques for solving such problems. (1) Technology using positively charged fine particles treated with a silane coupling agent (see JP-A-53-66235, JP-A-56-123550, and JP-B-Sho 53-22477). (2) Technology using positively charged fine particles treated with silicone oil (Japanese Unexamined Patent Publication No. 1983-60754,
(See Publication No. 59-187359). [Problems to be Solved by the Invention] However, as in techniques (1) and (2) above, positively charged fine particles treated with a silane coupling agent or silicone oil are used and mixed with the toner. Even if they are attached to the surface of the toner particles, when subjected to physical force such as stirring in the developing device, the fine particles will scatter from the surface of the toner particles, and as a result, the toner will not have an appropriate amount of charge. The fine particles that are not positively triboelectrically charged and scattered become attached physically or electrostatically to the inner wall of the developing device, the developing sleeve disposed inside the developing device, the regulating blade, the carrier particle surface, etc., and the toner If the triboelectricity is inhibited and the accumulation due to adhesion of fine particles becomes excessive, the fine particles and toner particles will be triboelectrically charged, and the toner particles will be charged with opposite polarity, that is, negatively charged, and as a result, the toner will scatter. There are problems in that the inside of the apparatus becomes contaminated, and in the final fixed image, fogging occurs and the image density decreases, resulting in an unclear image. Further, when image formation is repeated many times, the image gradually becomes less clear, resulting in a defective image at an early stage, resulting in low durability. In particular, when using fine particles treated with a silane coupling agent, it is difficult to completely cover the surface of the fine particles with the silane coupling agent, and as a result, negatively charged sites and hydrophilic sites of the fine particles remain. , the positive chargeability of the toner decreases due to the remaining negatively chargeable sites, and furthermore, the toner becomes negatively chargeable, causing a lot of fogging in the final fixed image, and also due to the remaining hydrophilic side. As a result, the triboelectric charging ability becomes unstable when environmental conditions change, resulting in contamination of the inside of the device due to toner scattering, fogging in the final fixed image, and There are problems in that the image density decreases due to a decrease in the transfer rate in the transfer process, and image unevenness occurs due to toner scattering, resulting in an unclear image. In addition, especially when using fine particles treated with silicone oil, the surface of the fine particles is covered with a sticky oily substance, so such fine particles are mixed with the toner to coat the surface of the toner particles. It is difficult to improve the fluidity of the toner even if it is attached to the toner, physical aggregation may occur due to silicone oil, and fine particles may adhere to the inner wall of the developing device, the developing sleeve, the regulating blade, etc. to reduce the positive charging ability of the toner,
As a result, there is a problem in that the developability is lowered, contamination occurs due to toner scattering, and the final fixed image becomes unclear with a lot of fog and image gaps. In addition, in the image forming process, the toner image formed on the surface of the photoreceptor through the development process is subjected to a transfer process, and in this transfer process, it is transferred to a transfer material made of ordinary paper or the like. As the transfer means, it is preferable to use electrostatic transfer means that utilizes electrostatic force. However, as in the techniques (1) and (2) above, the toner formed on the surface of the photoreceptor is developed with a toner composed of fine particles treated with a silane coupling agent or silicone oil. Images are difficult to transfer well using electrostatic transfer means due to insufficient charge and strong adhesion to the surface of the photoreceptor.
As a result, there are problems in that image unevenness and image missing occur in the final fixed image, and image density decreases. Further, the photoconductor after the toner image has been transferred in the transfer process is then subjected to a cleaning process, in which the toner remaining on the surface of the photoconductor after the transfer process is removed, and the surface of the photoconductor is cleaned. Cleaned. However, as in the techniques (1) and (2) above, toners constructed using fine particles treated with a silane coupling agent or silicone oil,
Due to the strong physical and electrostatic adhesion force to the surface of the photoconductor, it is difficult to completely clean the residual toner, and as a result, some toner remains on the photoconductor and is not used for the next image formation. have a negative impact,
There is a problem that the image becomes unclear. Further, the transfer material onto which the toner image has been transferred in the transfer step is subjected to a fixing step, and the toner image is heated or pressurized by a heat roller to be fixed to the transfer material, thereby forming a final fixed image. However, as in the techniques (1) and (2) above, toner composed of fine particles treated with a silane coupling agent or silicone oil tends to transfer and adhere to the surface of the heated roller. As a result, the so-called offset phenomenon occurs, in which the toner that has adhered to the heat roller is transferred again to the transfer material that is sent next, staining the image.Also, when the toner that has adhered to the heat roller solidifies, this causes the heat roller to become stained. There is a problem that the surface is damaged and the durability of the heat roller is significantly reduced. [Object of the Invention] The present invention has been made based on the above-mentioned circumstances, and its objects are (1) to provide an electrostatic image developer having good positive chargeability and excellent moisture resistance; (2) To provide an electrostatic image developing method capable of satisfactorily developing a negative electrostatic latent image formed on an organic photoconductive photoreceptor without scattering of developer particles; (3) To provide an image forming method that can stably form images of high image density, fog-free, and good image quality many times without being affected by environmental conditions. [Means for solving the problems] The electrostatic image developer of the present invention has the general formula (1) (R represents an alkylene group or a phenylene group, and x and y each represent an integer of 1 or more.) Silicone oil having an epoxy group with an epoxy equivalent of 20 to 10,000 and a viscosity of 40 to 20,000 cps at 25°C It consists of fine silica particles whose surface has been treated and further treated with an amino compound, and the average particle diameter of the primary particles is 5 to 500 mμ.
Inorganic fine particles with a specific surface area of 20 to 500 m ² /g by the BET method (hereinafter also referred to as "specific inorganic fine particles").
It is characterized by being mixed with the toner in an amount of 0.1 to 5% by weight. In the electrostatic image developing method of the present invention, a negative electrostatic latent image formed on the surface of a photoreceptor (hereinafter also referred to as "organic photoreceptor") made of an organic photoconductive semiconductor is transferred to the specific inorganic fine particles. It is characterized in that it is developed using a mixed electrostatic image developer. The image forming method of the present invention includes a latent image forming step of forming a negative electrostatic latent image on the surface of the organic photoreceptor, and an electrostatic image development step in which the electrostatic latent image is mixed with the specific inorganic fine particles. a development step in which the toner image obtained by development is electrostatically transferred to a transfer material; and a cleaning step in which the developer remaining on the surface of the organic photoreceptor is cleaned with a cleaning blade after the transfer step. and a fixing step of heating and fixing the toner image on the transfer material using a heat roller fixing device having a heat roller coated with a fluorine-based resin or a silicone-based resin. [Operations and Effects of the Invention] Since the electrostatic image developer of the present invention contains specific inorganic fine particles, it has good positive chargeability and excellent moisture resistance. That is, when the surface of the inorganic fine particles is treated with silicone oil having an epoxy group, the silicone oil having an epoxy group binds to the hydrophilic sites and negatively charged sites on the surface of the inorganic fine particles, and this binds firmly to the surface. Moreover, the presence of epoxy groups suppresses the tackiness of the silicone oil, and as a result, the silicone oil with epoxy groups imparts good hydrophobicity to the inorganic fine particles, and this By further treating the surface of the inorganic fine particles with an amino compound, the inorganic fine particles are given positive chargeability, and the positive chargeability of the inorganic fine particles is stably exhibited even under high humidity environmental conditions, resulting in excellent positive chargeability. A chargeable developer can be obtained. In addition, the specific inorganic fine particles mentioned above have good adhesion to the developer and are firmly held by the developer particles, so that when the developer is stirred in the developing device, This prevents inorganic fine particles from transferring and adhering to the inner wall of the developing device, the developing sleeve, the regulation blade, etc., and as a result, the developer exhibits stable positive chargeability even when performing the image forming process multiple times. become. Since the specific inorganic fine particles impart high fluidity to the developer, the developer particles do not aggregate and are triboelectrically charged in a stable state. According to the electrostatic image developing method of the present invention, an electrostatic image developer containing the above-mentioned specific inorganic fine particles,
Since the negative electrostatic latent image formed on the surface of a photoreceptor made of an organic photoconductive semiconductor is developed, the organic photoreceptor can be easily processed without sacrificing the advantages of organic photoreceptors such as low production cost and non-toxicity. A negative electrostatic latent image formed on the image can be developed satisfactorily without scattering of developer particles. In other words, since the above-mentioned developer has excellent positive chargeability, it becomes positively charged with an appropriate amount of charge, and therefore, the developer particles are stably held in the development sleeve and enter the development space. This makes it possible to prevent contamination caused by scattering of developer particles.
In addition, as mentioned above, the fluidity of the developer is excellent, so it is possible to form a magnetic brush of uniform and uniform developer on the developing sleeve, and therefore good development can be achieved using the magnetic brush development method. It becomes possible to do so. According to the image forming method of the present invention, since the electrostatic image developer contains the above-mentioned specific inorganic fine particles and has excellent positive chargeability, in the developing step, the non-image on the organic photoreceptor is As a result, it is possible to obtain a clear image free from fog in the final fixed image. In addition, since the specific inorganic fine particles give the developer suitable releasability, the physical adhesion to the surface of the organic photoreceptor is small. Transfer can be performed, and it is possible to form a clear image with high image density and no image unevenness. In addition, as described above, the transferability of the developer is good, so only a small amount of developer remains on the organic photoreceptor after the transfer process, making it easy to clean the remaining developer in the cleaning process. Moreover, as mentioned above, since the developer has suitable mold releasability, the adhesion of the developer to the organic photoreceptor is small, and as a result, the developer can be easily cleaned using a cleaning blade. becomes possible. Furthermore, since the cleaning properties of the developer are good, it is possible to achieve good cleaning with a small pressure contact force of the cleaning blade against the photoreceptor. This prevents premature deterioration of the characteristics of the organic photoreceptor due to abrasion, and the service life of the organic photoreceptor can be significantly extended. In addition, in the fixing process, the specific inorganic fine particles are present between the surface of the molten developer and the heat roller, so that a mold release effect is obtained by the specific inorganic fine particles, and the developer is transferred to the heat roller. This also prevents developer from accumulating in the minute grooves of the heat roller, and since the heat roller is coated with fluorocarbon resin or silicone resin, the transfer of developer to the heat roller is prevented. Transfer adhesion is further prevented, and as a result, image stains caused by offset phenomena can be prevented. In addition, since the surface of the specific inorganic fine particles is covered with silicone oil having an epoxy group and further covered with an amino compound, there is little risk of the surface of the heat roller being damaged by the specific inorganic fine particles, and the surface of the heat roller is It becomes possible to significantly extend the service life, and excellent offset resistance can be stably obtained over a long period of time. [Specific Structure of the Invention] The electrostatic image developer of the present invention has a surface treated with a silicone oil having an epoxy group and further contains inorganic fine particles treated with an amino compound. As the silicone oil having an epoxy group, for example, one represented by the following general formula (1) can be used. General formula (1) (R represents an alkylene group or a phenylene group, and x and y each represent an integer of 1 or more.) In addition, the epoxy equivalent of the silicone oil having an epoxy group is within the range of 200 to 10,000, and 25 Those having a viscosity in the range of 40 to 20,000 cps at °C are used. When the epoxy equivalent is too small, stable positive triboelectric charging properties may not be obtained, fogging may occur, and durability may be reduced.On the other hand, when the epoxy equivalent is too large, moisture resistance and durability may be reduced. There are cases. In addition, when the viscosity is too low, durability may decrease due to increased stickiness, while when the viscosity is too high, the surface treatment of the inorganic fine particles becomes poor, resulting in unstable positive triboelectric charging properties. durability may decrease. As specific substances for the silicone oil having an epoxy group, for example, commercially available products shown in Table 1 below can be preferably used.

[Specific examples]

Hereinafter, specific examples and comparative examples of the present invention will be described, but the present invention is not limited to these examples. (Manufacture of inorganic fine particles) (1) Inorganic fine particles A (for the present invention) is a silicone oil having an epoxy group,
A first treatment liquid was prepared by dissolving 20 parts by weight of "X-22-342" (manufactured by Shin-Etsu Chemical Co., Ltd.) in 80 parts by weight of hexane. Next, 100 parts by weight of silica fine particles "Aerosil 200" (manufactured by Nippon Aerosil Co., Ltd.) was placed in a mixer, and while rotating, 100 parts by weight of the above-mentioned first treatment liquid was gradually added dropwise. These were placed in a flask and heated and dried for 1 hour while stirring, thereby obtaining inorganic fine particles whose surfaces were treated with silicone oil having an epoxy group. Then, 20 parts by weight of hexamethylene diamine, which is an amino compound, was dissolved in 80 parts by weight of hexane.
A second treatment solution was prepared. 100 parts by weight of inorganic fine particles whose surface was treated with the silicone oil having an epoxy group were treated in the same manner as above using 100 parts by weight of the second treatment liquid, and the surface was further treated with an amino compound. Inorganic fine particles were obtained. This will be referred to as "inorganic fine particles A." This inorganic fine particle A is
The average particle diameter of the primary particles was 12 mμ, and the specific surface area was 90 m ² /g by the BET method. (2) Inorganic fine particles B (for the present invention) silicone oil having an epoxy group,
A first treatment liquid was prepared by dissolving 15 parts by weight of "SF-8411" (manufactured by Toray Silicone) in 85 parts by weight of toluene. Next, the same process as in the production of inorganic fine particles A was carried out except that 100 parts by weight of this first treatment liquid was used to obtain inorganic fine particles whose surfaces were treated with silicone oil having an epoxy group. Then, 10 parts by weight of diethylenetriamine, which is an amino compound, was dissolved in 90 parts by weight of hexane to prepare a second treatment liquid. 100 parts by weight of inorganic fine particles whose surface was treated with the silicone oil having an epoxy group were treated in the same manner as above using 100 parts by weight of the second treatment liquid, and the surface was further treated with an amino compound. Inorganic fine particles were obtained. These will be referred to as "inorganic fine particles B". This inorganic fine particle B is
The average particle diameter of the primary particles was 7 mμ, and the specific surface area was 122 m ² /g by the BET method. (3) Inorganic fine particles C (for the present invention) is a silicone oil having an epoxy group,
A first treatment liquid was prepared by dissolving 10 parts by weight of "SF-8413" (manufactured by Toray Silicone) in 90 parts by weight of toluene. Next, 100 parts by weight of the first treatment liquid and silica fine particles "Aerosil 300" (manufactured by Nippon Aerosil Co., Ltd.) were added.
Except that 100 parts by weight was used, inorganic fine particles whose surfaces were treated with epoxy group-containing silicone oil were obtained in the same manner as in the production of inorganic fine particles A. Then, 15 parts by weight of triethylenetetramine, which is an amino compound, was dissolved in 85 parts by weight of hexane.
A second treatment solution was prepared. 100 parts by weight of inorganic fine particles whose surface was treated with the silicone oil having an epoxy group were treated in the same manner as above using 100 parts by weight of the second treatment liquid, and the surface was further treated with an amino compound. Inorganic fine particles were obtained. This will be referred to as "inorganic fine particles C." This inorganic fine particle C is
The average particle diameter of the primary particles was 13 mμ, and the specific surface area was 72 m ² /g by the BET method. (4) Inorganic fine particles D (for comparison) Silica fine particles "Aerosil 200" (manufactured by Nippon Aerosil Co., Ltd.) were placed in a closed Henschel mixer heated to 100℃, and amino group-containing silicone oil was added to the silica fine particles using isopropyl. Solution dissolved in alcohol (viscosity 1200 cps, amino equivalent
3500) was stirred at high speed while spraying at a rate such that the amount of the amino group-containing silicone oil treated was 2.0% by weight, and then dried at a temperature of 150°C, so that the surface was treated with the amino group-containing silicone oil. Inorganic fine particles for comparison were obtained. These are referred to as "inorganic fine particles D." (5) Inorganic fine particles E (for comparison) Silica fine particles "Aerosil 200" (manufactured by Nippon Aerosil Co., Ltd.) were placed in a closed Henschel mixer heated to 70°C, and an amino group-containing silane coupling agent was added to the silica fine particles. A solution of γ-aminopropyltriethoxysilane dissolved in alcohol was stirred at high speed while being sprayed at a rate such that the amount of the amino group-containing silane coupling agent treated was 5.0% by weight, and then at a temperature of 120°C. Comparative inorganic fine particles were obtained which were dried at ℃ and whose surfaces were treated with an amino group-containing silane coupling agent.
These are referred to as "inorganic fine particles E." (6) Inorganic fine particles F (for comparison) A treatment solution was prepared by dissolving 20 parts by weight of silicone oil having an epoxy group and 20 parts by weight of hexamethylene diamine in the production of inorganic fine particles A in 160 parts by weight of hexane. of silica fine particles "Aerosil 200" (manufactured by Nippon Aerosil Co., Ltd.)
100 parts by weight was treated in the same manner as inorganic fine particles A to obtain comparative inorganic fine particles. These are referred to as "inorganic fine particles F."<Example1> (1) Production of toner 100 parts by weight of polystyrene-n-butyl acrylate copolymer (copolymerization weight ratio = 82:18) and carbon black "Mogull L" (manufactured by Cabot Co., Ltd.)
10 parts by weight of the dye and 2 parts by weight of the metal-containing dye were mixed in a V-type blender, then melt-kneaded with two rolls, cooled, coarsely ground with a hammer mill, finely ground with a jet mill, and then Classified using a wind classifier to determine the average particle size.
A non-magnetic toner of 11.0 μm was obtained. This is referred to as "toner 1". (2) Production of developer The inorganic fine particles A are added to 50 parts by weight of the above toner 1.
By adding 0.5 parts by weight of and mixing these with a Henschel mixer, inorganic fine particles are attached or implanted onto the surface of the toner particles and retained, and then iron powder "DSP138" (manufactured by Nippon Tetsuko Kogyo Co., Ltd.) is added to these. The electrostatic image developer of the present invention, which is a two-component developer, was obtained by mixing 950 parts by weight of the carrier. This will be referred to as "Developer 1". (3) Live-action test Γ Test 1 (live-action test under normal humidity environment conditions) An organic photoreceptor for forming a negative electrostatic latent image,
A contact type magnetic brush developer, a corona transfer device that generates alternating current corona discharge, a heat roller with a diameter of 20φ whose surface layer is made of Teflon (polytetrafluoroethylene manufactured by Dupont), and a silicone rubber surface layer "KE-1300RTV". ``U-Bix1500MR'' electrophotographic copying machine equipped with a heat roller fixing device made of a back-up roller made by Shin-Etsu Chemical Co., Ltd. and a cleaning device having a cleaning blade made of urethane rubber.
Temperature 20
A photocopying test was conducted in which a copy image was continuously formed 30,000 times using the above developer 1 under normal temperature environmental conditions of 60% relative humidity and 60% relative humidity, and the following items were evaluated. The results are shown in Table 2 below. The above-mentioned organic photoreceptor has a negatively chargeable two-layer structure photosensitive layer formed using an anthrone pigment as a carrier generating substance and a carbazole derivative as a carrier transporting substance, and a rotating drum-shaped aluminum conductive photosensitive layer. It is constructed by laminating layers on a support. The surface potential (highest potential) of the organic photoreceptor when it is charged is -700V, the gap (Dsd) between the photoreceptor and the developing sleeve in the developing space is 0.9 mm, and the distance between the tip of the regulating blade and the developing sleeve ( Hcut) is 0.6 mm, the magnet is fixed, the magnetic flux density on the surface of the developing sleeve is 800 Gauss, and the bias voltage applied to the developing sleeve is a DC voltage of -
It is 100V. Fog Fog was determined by measuring the relative density of multiple images of a white background area with a document density of 0.0 using a "Sakura Densitometer" (manufactured by Konishiroku Photo Industry Co., Ltd.). In addition, the evaluation is based on the white background reflection density as 0.0, and the evaluation is "○" when the relative density is less than 0.01, and 0.03 when it is 0.01 or more.
If it is less than 0.03, it is marked as "△", and if it is 0.03 or more, it is marked as "x". Image Density Using a "Sakura Densitometer" (manufactured by Konishiroku Photo Industry Co., Ltd.), the relative density of multiple images of a white background area with a document density of 0.0 was measured. Image quality The reproduced image has three characteristics: image omission, image unevenness, and clarity.
Judgment was made visually from two points. The evaluation was ``x'' if it was poor and had a practical problem, ``△'' if it was slightly defective but at a practical level, and ``○'' if it was good. Toner scattering Visually observe the inside of the copier and the copied images,
``○'' indicates that there is almost no toner scattering and is in good condition; ``△'' indicates that some toner scattering is observed but it is at a practical level; ``×'' indicates that there is a lot of toner scattering and there is a problem in practical use. ”. Cleanability After repeated image formation, the surface of the organic photoreceptor was visually observed immediately after being cleaned with a cleaning blade, and judgment was made based on the presence or absence of deposits on the surface of the organic photoreceptor. The evaluation is "○" if there is almost no deposits observed and the product is in good condition, "△" if some deposits are observed but at a practical level, and "△" if a lot of deposits are observed and there is a problem in practical use. was marked as "×". Durability of fixing device Judgment was made based on the occurrence of an offset phenomenon, occurrence of paper jams, and staining of the back side of transfer paper due to dirt on the heat roller and back-up roller that constitute the fixing device. The evaluation was rated "x" if it was poor and had a practical problem, "△" if it was slightly poor but at a practical level, and "○" if it was good. Γ Test 2 (Live-action test under high-humidity environmental conditions) In addition to setting the environmental conditions to a high-humidity environment with a temperature of 30° C. and a relative humidity of 80%, a live-photography test was also conducted in the same manner, and each of the above items was evaluated. The results are shown in Table 3 below. <Example 2> A developer was obtained in the same manner as in Example 1, except that 0.4 parts by weight of inorganic fine particles B was used instead of inorganic fine particles A.
This will be referred to as "Developer 2". A photographic test was carried out in the same manner as in Example 1, except that this developer 2 was used, and evaluations were made in the same manner. The results are shown in Tables 2 and 3 below. <Example 3> A developer was obtained in the same manner as in Example 1, except that 0.6 parts by weight of inorganic fine particles C for comparison was used instead of inorganic fine particles A in producing the developer of Example 1. . This will be referred to as "Developer 3". A photographic test was carried out in the same manner as in Example 1, except that this developer 3 was used, and evaluations were made in the same manner. The results are shown in Tables 2 and 3 below. <Comparative Example 1> A developer was obtained in the same manner as in Example 1, except that 0.4 parts by weight of Comparative Inorganic Fine Particles D was used instead of Inorganic Fine Particles A in producing the developer of Example 1. . This is referred to as "comparative developer 1." A photographic photographic test was carried out in the same manner as in Example 1, except that this comparative developer 1 was used, and evaluations were made in the same manner. The results are shown in Tables 2 and 3 below. <Comparative Example 2> A developer was obtained in the same manner as in Example 1, except that 0.4 parts by weight of comparative inorganic fine particles E was used instead of inorganic fine particles A in producing the developer of Example 1. . This is referred to as "comparative developer 2." A photographic test was carried out in the same manner as in Example 1, except that this comparative developer 2 was used, and evaluations were made in the same manner. The results are shown in Tables 2 and 3 below. <Comparative Example 3> A developer was obtained in the same manner as in Example 1, except that 0.4 parts by weight of comparative inorganic fine particles F was used in place of inorganic fine particles A. This is referred to as "comparative developer 3." A photographic test was carried out in the same manner as in Example 1, except that this comparative developer 3 was used, and evaluations were made in the same manner. The results are shown in Tables 2 and 3 below.

【table】

【table】

[Table] As can be understood from the results in Tables 2 and 3, developers 1 to 3 of the present invention have good toner triboelectric charging properties and fluidity, and therefore are effective in the development process. The negative electrostatic latent image formed on the organic photoreceptor by the magnetic brush development method can be developed well without toner scattering, and in the transfer process, the electrostatic transfer means can achieve a high transfer rate. In addition, in the cleaning process, a cleaning blade with a simple structure can perform good cleaning, and in the fixing process, a hot roller fixing device can perform good fixing without causing offset phenomenon. As a result, it is possible to form a good image with clear image quality without fogging, image missing, or image unevenness, and with high image density. Even when performing the image forming process many times, the heat roller and back-up roller in the heat roller fixing device do not get dirty, and the usable life of the roller is significantly extended.
Furthermore, good images can be stably formed even under high humidity environmental conditions. On the other hand, according to Comparative Developer 1, since comparative inorganic fine particles D whose surfaces were treated with amino group-containing silicone oil are used, the triboelectric charging properties of the toner are poor, resulting in a lot of fogging. This results in an unclear image with low image density. Furthermore, when the image forming process is performed many times, the blur of the image gradually increases, resulting in a defective image at an early stage. In addition, according to Comparative Developer 2, since comparative inorganic fine particles E whose surfaces were treated with an amino group-containing silane coupling agent are used, the surface of the inorganic fine particles is completely coated with the amino group-containing silane coupling agent. Therefore, the negatively charged sites and hydrophilic sites of the inorganic fine particles remain, resulting in poor triboelectric charging properties of the toner, resulting in an unclear image with a lot of fog and low image density. Further, the triboelectric charging properties become unstable due to the influence of humidity, and therefore, under high humidity environmental conditions, fogging occurs significantly, image density decreases considerably, and images become significantly blurred. Furthermore, according to Comparative Developer 3, since the silicone oil having an epoxy group and the amino compound are treated simultaneously, the reaction between the epoxy group and the amine occurs preferentially, producing a reaction product having a hydroxyl group, and the inorganic fine particles F There are many hydroxyl groups on the surface of the toner, which reduces the positive chargeability and makes it more susceptible to humidity.As a result, the triboelectricity of the toner becomes poor, resulting in an unclear image with a lot of fog and low image density. Become. In addition, triboelectric charging properties rapidly and unstablely decrease due to the influence of humidity, resulting in significant fogging under high-humidity environmental conditions.
In addition, the image density is considerably reduced and the image becomes significantly blurred. Furthermore, the reaction products tend to cause contamination, contaminating the surface of the photoreceptor and the fixing roller, thereby reducing cleaning performance and durability of the fixing device. Furthermore, when we conducted a continuous photographic test of 50,000 times using Developers 1 to 3 according to the present invention and applying the developing method according to the present invention, Tables 2 and 3 showed that
Good results similar to those shown in the table were obtained. In addition, when we conducted a continuous photographing test over 70,000 times using the developers 1 to 3 according to the present invention and applying the image forming method according to the present invention, the same good results as shown in Tables 2 and 3 were obtained. was gotten.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of an electrostatic image developing apparatus that can be suitably used to carry out the electrostatic image developing method of the present invention, and FIG. FIG. 2 is an explanatory diagram showing an example of an image forming apparatus that can be suitably used. 10...organic photoreceptor, 10A...conductive support, 10B...photosensitive layer, 11...developing sleeve,
12... Magnet body, 13... Regulation blade, 23...
...Developer layer (magnetic brush), 24...Development space,
30...cabinet, 31...manuscript, 32...
Original stage, 40...Transfer paper, 50...Organic photoreceptor, 51...Corona charger, 52...Exposure optical system, 53...Magnetic brush developer, 54...Electrostatic transfer device, 56... Blade type cleaning device, 70
...Heat roller fuser.

Claims (1)

[Claims] 1 General formula (1) (R represents an alkylene group or a phenylene group, and x and y each represent an integer of 1 or more.) Silicone oil having an epoxy group with an epoxy equivalent of 200 to 10,000 and a viscosity of 40 to 20,000 cps at 25°C It consists of fine silica particles whose surface has been treated and further treated with an amino compound, and the average particle diameter of the primary particles is 5 to 500 mμ.
An electrostatic image developer comprising a toner mixed with 0.1 to 5% by weight of inorganic fine particles having a specific surface area of 20 to 500 m ² /g by BET method. 2 A negative electrostatic latent image formed on the surface of a photoreceptor made of an organic photoconductive semiconductor is expressed by the general formula (1). (R represents an alkylene group or a phenylene group, and x and y each represent an integer of 1 or more.) Silicone oil having an epoxy group with an epoxy equivalent of 200 to 10,000 and a viscosity of 40 to 20,000 cps at 25°C It is made of silica fine particles whose surface has been treated with silica and further treated with an amino compound, and the average particle size of the primary particles is 5 to 500 mμ,
An electrostatic image developing method characterized by developing with an electrostatic image developer prepared by mixing toner with 0.1 to 5% by weight of inorganic fine particles having a specific surface area of 20 to 500 m ² /g by BET method. 3. A latent image forming step of forming a negative electrostatic latent image on the surface of a photoreceptor made of an organic photoconductive semiconductor, and this electrostatic latent image is expressed by the general formula (1). (R represents an alkylene group or a phenylene group, and x and y each represent an integer of 1 or more.) Silicone oil having an epoxy group with an epoxy equivalent of 200 to 10,000 and a viscosity of 40 to 20,000 cps at 25°C It consists of fine silica particles whose surface has been treated and further treated with an amino compound, and the average particle diameter of the primary particles is 5 to 500 mμ.
A developing process in which inorganic fine particles having a specific surface area of 20 to 500 m ² /g by the BET method are mixed with a toner in an amount of 0.1 to 5% by weight, and an electrostatic image developer is used. a cleaning step in which developer remaining on the surface of the photoconductor is cleaned with a cleaning blade after the transfer step; and a heat roller coated with fluorine-based resin or silicone-based resin. A fixing step of heating and fixing the toner image on the transfer material using a heat roller fixing device having a heat roller fixing device.